Frequency and Clinical Correlates of Thyroid Dysfunction in Patients With Type 2 Diabetes Mellitus: A Cross-Sectional Study.

BACKGROUND

Thyroid dysfunction commonly coexists with type 2 diabetes mellitus (T2DM), compounding metabolic derangements and increasing the risk of complications. Despite its clinical significance, the prevalence and spectrum of thyroid dysfunction among South Asian patients with T2DM remain incompletely characterized. This study aimed to determine the frequency and types of thyroid dysfunction in patients with T2DM and to examine its associations with demographic characteristics, glycemic control, metabolic parameters, and microvascular complications.

METHODS

A cross-sectional study was conducted over a six-month period at a tertiary care hospital in Lahore, Pakistan. Adult patients with confirmed T2DM were enrolled consecutively after informed consent. Clinical assessment included age, gender, body mass index (BMI), duration of diabetes, blood pressure, and glycated hemoglobin (HbA1c), along with documentation of microvascular complications (retinopathy, nephropathy, neuropathy), dyslipidemia, and thyroid profile.

RESULTS

A total of 442 patients were included (mean age 56.12 ± 9.47 years; 228 males, 214 females). Hypothyroidism was present in 105 (23.8%), subclinical hypothyroidism in 66 (14.9%), euthyroid status in 251 (56.8%), and hyperthyroidism in 20 (4.5%). The mean BMI was 26.40 ± 4.33 kg/m², with overweight and obesity most common in hypothyroid (38.1% and 31.4%, respectively) and subclinical hypothyroid (63.6% and 16.7%, respectively) patients. Mean diabetes duration was longest in hypothyroidism (10.37 ± 5.02 years), compared to subclinical hypothyroidism (6.55 ± 5.28 years), euthyroid (5.52 ± 3.69 years), and hyperthyroidism (7.00 ± 4.57 years). Hypothyroid patients reported the poorest glycemic control (mean HbA1c 9.45 ± 1.64%). Microvascular complications (retinopathy 30.5%, nephropathy 20.0%, neuropathy 27.6%) and dyslipidemia (63.8%) were markedly elevated in hypothyroid cases. Statistically significant differences were observed for age, BMI, diabetes duration, and HbA1c across thyroid status groups (all p < 0.001). Thyroid-stimulating hormone (TSH) correlated positively with age (r=0.201), BMI (r=0.131), diabetes duration (r=0.398), and HbA1c (r=0.414).

CONCLUSION

Thyroid dysfunction, particularly hypothyroidism, was frequent in T2DM and associated with older age, female gender, longer diabetes duration, adverse metabolic profiles, and greater burden of microvascular complications, underscoring the importance of routine thyroid assessment in diabetic care.